This invention relates to the field of hand tools for pulling tightly fit sleeves or tubes from their mounting enclosure.
Wendler U.S. Pat. No. 4,110,886 discloses a tool for removing a diesel injector. This tool, as many of the tools disclosed below, involves the use of a journaled impact hammer or cylindrical driving member sliding on a shaft to provide an impact pulling force. The active end of the tool is a head sized to closely fit within the central bore of a diesel injector, with a transverse, spring loaded pin which is adapted to mate with the transverse fuel passages of the injector. Means are provided for limiting the travel of the pin into the transverse fuel passage and for removing the pin from the transverse fuel passage so as to remove the injector from the head.
Brooks U.S. Pat. No. 3,529,497 discloses, within the context of a dowel removing tool, a reciprocating plunger tool ending in an active tip which has an outward taper journaled to fit within an outer cylindrical member. The center bore of the tip of the tool is slit for expansion or contraction and provided with internal threads. The tool is manipulated by fitting the internal threads over a dowel pin and then driving the cylindrical member down over the taper to closely engage the threads into the dowel pin. The hammer is then reversed to impose a lifting force on the dowel pin, removing the pin. The dowel pin is solid and therefore, resistant to compressive forces. Only friction changes the threaded section within the cylindrical member during withdrawal.
Hawkins U.S. Pat. No. 4,734,972, discloses a tool for removing a tube plug, a plug for sealing an unusable tube in a boiler. Such a tube plug is an expandable plug set with a tool in which a reverse tapered face on a draw bar (44) expands a toothed plug (42) into the walls of the tube 28 forming a tight seal which is left in place to block passage of fluids through the tube. The resulting tube plug is not split but is a solid plug, permanently expanded by deformation into a bonded relationship with the sidewall of a tube. The remainder of the patent discloses a particular concentric machine for drilling out and removing such an otherwise permanently affixed plug.
U.S. Pat. No. 4,724,608 discloses an apparatus using a pulling shaft with a tapered lowered end, which expands a split collar gripping unit (see FIG. 2 of the patent) so as to engage a shoulder (item 150) with the back of a bushing (10) allowing the bushing to be pulled by the essentially linear force imposed through the shoulder of the bushing port.
A related device, a Bearing Puller, is shown in Hacker U.S. Pat. No. 4,507,838. The puller utilizes a tapered plug to expand an otherwise contracted cylinder which is inserted through the axis of the bearing and then expanded to engage the rear shoulders.
A third form is shown in Patton U.S. Pat. No. 2,380,068 as an oil seal puller. The tapered internal expanding plug is reversed in direction and is driven into the toothed expansion member, forcing it apart to engage the seal.
Filer U.S. Pat. No. 4,280,274 discloses an apparatus for extracting tubes from a heat exchanger in which a multistep apparatus is disclosed. A first split tap thread into the tubes, which are essentially cylindrical and smoothwalled. A separate engaging device, much like the oil seal puller of Patton, is fit into an internal receiving shoulder of the screwed in drill tap to provide for a removing force to pull both drill tap and tube from the boiler.
Both Hawkins and Filer teach that it is necessary to thread an extraction removal extractor unit into the wall of the tube in order to obtain a sufficient contact to provide a suitable pulling force. The patents teaching a reverse expansion device, such as Parrott or Hacker teach such a device not for gripping of the item to be removed but rather for expanding shoulders behind the item so as to impose a pulling force lengthwise along the tube in its strong direction. Brooks, which does teach the use of a tapered end sleeve for compressing a threaded member into an item to be removed, teaches the inward compression against a solid dowel. It would appear that inverting the structure of Brooks would drive the walls of the tube more solidly into the backing support, increasing the friction and resistance to removal; both Filer and Hawkins teach that it is necessary to thread or tap a tube to be removed, screwing a threaded removal into this tap. Hawkins further teaches that expanding a toothed element within a thin walled tube against a backing support is a method of plugging rather than removing the tube.